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Number.isInteger

The Number.isInteger() method determines whether the passed value is an integer.

Syntax

Number.isInteger(value)

Parameters

value
The value to be tested for being an integer.

Return value

A Boolean indicating whether or not the given value is an integer.

Description

If the target value is an integer, return true, otherwise return false. If the value is NaN or Infinity, return false. The method will also return true for floating point numbers that can be represented as integer.

Examples

Using isInteger

Number.isInteger(0);         // true
Number.isInteger(1);         // true
Number.isInteger(-100000);   // true
Number.isInteger(99999999999999999999999); // true

Number.isInteger(0.1);       // false
Number.isInteger(Math.PI);   // false

Number.isInteger(NaN);       // false
Number.isInteger(Infinity);  // false
Number.isInteger(-Infinity); // false
Number.isInteger('10');      // false
Number.isInteger(true);      // false
Number.isInteger(false);     // false
Number.isInteger([1]);       // false

Number.isInteger(5.0);       // true
Number.isInteger(5.000000000000001); // false
Number.isInteger(5.0000000000000001); // true

Polyfill

Number.isInteger = Number.isInteger || function(value) {
  return typeof value === 'number' && 
    isFinite(value) && 
    Math.floor(value) === value;
};

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
isInteger 34 12 16 No 21 9
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
isInteger ≤37 34 16 21 9 2.0
Server
Node.js
isInteger 0.12

See also

  • The Number object it belongs to.

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isInteger